Amir Memon, an iOS software engineer at Facebook, gave us permission to republish his answer. This answer reflects his personal opinion and not Facebook's.

Because he is just that awesome.

There are several reasons why we "approve" of him:

The story: He built this billion user and billion dollar company from his dorm room, overcame one obstacle after another, and assembled a company with the most talented employees in the world.

The principles: He is dead-focused on "making the world more open and connected." The guy doesn't waver; all the investments in R&D and acquisitions have been along these lines.

The heart: He was the biggest donor of 2013, and is generally a minimalist. He is clearly committed to Internet.org, even though that's not necessarily where the short term revenue increases are. We really feel he wants to change the world for the better.

The guts: What other CEO has the... guts... to purchase a chat company for $19B??? It's a very smart purchase for various reasons, but still, $19B! Even other Silicon Valley CEOs acknowledge Zuck's fearlessness:http://read.bi/1n24ctW

The wisdom: When we hear him speak, he gives us brain wrinkles. He has this uncanny ability to make all the right strategic moves, and when he explains the reasons for making those moves, it simply makes sense. Sure, mistakes have been made, and hindsight is 20/20, but at decision time, it was for all the right reasons.

The trust: He doesn't make all the decisions, in fact far from it. We feel entrusted and empowered to drive our features the way we feel is best for the people that use Facebook. This is drastically different from many top-down corporations. We're happy with the balance between management-mandated and grass-roots-inspired decision making.

The character: He wears T-Shirts and jeans, talks with humility, and he just seems generally very approachable. We like that.

The business: Facebook is a rock solid business that is rapidly increasing in revenue as we speak. It makes more than 70% more in revenue than it was making just one year ago.

The free food and perks: Yes, this makes us like him and the company too. He has the ability to put an end to it at any time, but he keeps it coming :-). If somebody gives me free cookies, I like them, this part is not rocket science.

And, no, having a lower approval rating is not a good thing. People don't "approve" because they agree with everything, rather they know that they have a say, and that their opinion matters. It's a good thing to like your boss.